Method and device for de-palletizing stacks of blanks

ABSTRACT

A device for de-palletizing stacks of blanks stacked on pallets with flat spacing layers disposed in-between, includes a displaceable gripping head and an insertion tool arranged approximately horizontally oriented on the gripping head. The insertion tool is positioned in front of at least one stack of blanks through displacement of the gripping head for being inserted with an approximately horizontal movement between the stack of blanks and the spacing layer for picking up the stack of blanks and for removing the picked up stack of blanks from the spacing layer through a displacement of the gripping head. At least one lifting mechanism is coupled to the gripping head for lifting up one side of the stack of blanks.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority of German Patent Application No. 101 62 101.9 filed Dec. 18, 2001. The disclosures of the foregoing priority application and of each and every U.S. and foreign patent and patent application mentioned herein, are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] The invention relates to a device for de-palletizing stacks of blanks, stacked on pallets with flat spacing layers disposed in-between, the device comprising at least one displaceable gripping head and at least one insertion tool arranged approximately horizontally oriented on the gripping head. This insertion tool can be positioned in front of at least one stack of blanks through displacement of the gripping head and can be inserted with an approximately horizontal movement between the stack of blanks and the spacing layer for picking up the stack of blanks. The tool can remove the picked up stack of blanks from the spacing layer by displacing the gripping head.

[0003] The invention furthermore relates to a method for de-palletizing stacks of blanks, stacked on a pallet with flat spacing layers disposed in-between, for which the at least one approximately horizontally oriented insertion tool that is attached to the at least one gripping head is positioned in front of at least one stack of blanks and is inserted approximately horizontally underneath the stack of blanks which is removed from the spacing layer by displacing the gripping head.

[0004] The invention furthermore relates to a method of de-palletizing stacks of blanks utilizing a device of the type described above.

[0005] Packaging machines with a high production output process large amounts of paper blanks or carton blanks. The packaging material blanks are provided on pallets to ensure a continuous feeding of packaging material blanks to the machines. The packaging material blanks are arranged on the pallets in stacks, so as to form layers, wherein respectively one spacing layer of cardboard or the like is disposed between the stack layers.

[0006] An insertion tool attached to a gripping head is inserted between the underside of the respective stack of blanks and the spacing layer below to remove a stack of blanks from a pallet of this type. The stack of blanks is lifted up through displacement of the gripping head and is transferred to a conveying system, which transports it to the respective packaging machine. To insert the tool between the stack of blanks to be removed and the spacing layer, the insertion tool is positioned in front of the stack of blanks by guiding the gripping head along three axes. Following the positioning, the insertion tool is inserted between the stack of blanks and the spacing layer with the aid of a horizontal movement of the insertion tool. In the process, it can happen that the insertion tool does not move smoothly into the space between the stack of blanks and the spacing layer, but is inserted into the spacing layer instead. When the insertion tool is lifted up, the spacing layer is also pulled up, so that the remaining stacks of blanks that are still positioned on the spacing layer are tossed around and, accordingly, are no longer arranged to enable removal in an orderly fashion.

[0007] De-palletizing devices and methods of this type are known from German patent documents DE 37 18 601 A1 and DE 196 53 953 A1, and European patent document EP 579 031 B1.

[0008] With the de-palletizing device known from DE 37 18 601 A1, the stack of blanks is deformed by a thrust member acting upon its top surface, such that a gap is created below the stack on the side that is assigned to the insertion tongue. The insertion tongue is inserted into this gap. However, the thrust member also deforms the stack of blanks.

[0009] EP 579 031 B1 proposes gripping a stack from the side and lifting it up, wherein any blanks not gripped during the lifting operation are lifted up with an airflow directed along the side of the stack from the top toward the support on the bottom. Following this, the stack is gripped from the top and bottom with the aid of a so-called clamping tongue and counter-pressure plate.

[0010] In addition, DE 196 53 953 A1 discloses that the spacing layer is deformed, with the aid of a pressure die, in a region where the insertion tongue is effective, such that the stack is fanned out on the side facing the insertion tongue. However, this hold-down member also causes the stack of blanks, arranged underneath, to be compressed or even damaged. In addition, gripping the outer stack of blanks on the pallet is problematic, since no supporting stack of blanks exists there for the hold-down member. Thus, the insertion tool can easily be inserted accidentally into the spacing layer and the outer stack of blanks underneath.

SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to improve the operation of de-palletizing stacks of blanks, so that the danger of damage to the spacing layers and the lower blanks in the stacks of blanks is reduced.

[0012] The above and other objects are accomplished according to the invention by the provision of a device for de-palletizing stacks of blanks stacked on pallets with flat spacing layers disposed in-between, comprising: at least one displaceable gripping head; at least one insertion tool arranged approximately horizontally oriented on the gripping head for being positioned in front of at least one stack of blanks through displacement of the gripping head and for being inserted with an approximately horizontal movement between the at least one stack of blanks and the spacing layer for picking up the at least one stack of blanks, for removing the picked up at least on stack of blanks from the spacing layer through a displacement of the gripping head; and at least one lifting means coupled to the gripping head for lifting up at least one side of the at least one stack of blanks.

[0013] By lifting the stack of blanks, at least one wedge-shaped gap is created between the underside of the stack of blanks and the spacing layer, into which the insertion tool can be inserted. Lifting up the stack means that no force acts upon the stack so as to deform it. Furthermore, the relative position of the blanks in the stack does not change. The stack is lifted with a vertical movement component. Within the framework of this invention, the complete stack of blanks and not just one side of the stack can also be lifted.

[0014] The lifting means can be activated prior to inserting the tool to make it easier to insert the tool into the gap.

[0015] One advantageous modification of the invention provides that the lifting means can be moved vertically, in particular pneumatically. For example, a pressure cylinder can be provided for guiding the movement of the lifting means, thus making it possible to reliably carry out exact movements.

[0016] A control and/or regulating unit is advantageously provided for the lifting means for realizing predetermined movements of the gripping head and/or the lifting means.

[0017] The lifting means on the gripping head is advantageously designed so that the side of the stack of blanks facing the insertion tool can be lifted. As a result, a gap-like opening that is large enough for inserting the tool forms between the stack of blanks and the spacing layer. In the process, the insertion tool is guided so that the spacing layer is not touched or damaged and, accordingly, stacks of blanks arranged underneath the spacing layer are also not damaged.

[0018] The lifting means of one preferred embodiment of the invention is provided with at least one suction element. The suction element is brought in contact with the stack of blanks to be picked up before it is lifted up. A vacuum is then supplied to the suction element, so that the stack of blanks is held by this suction element during the lifting operation.

[0019] To prevent damage to the stack of blanks, it is advantageous if the suction element is designed as an elastic and/or flexible suction cup. In addition, the suction element can thus attach itself easily to the surface of the stack of blanks.

[0020] According to one preferred modification of the invention, at least one clamping device is provided for the stack of blanks. After the stack is picked up, the clamping device can be used for lifting up the stack of blanks as well as during the displacement of the gripping head.

[0021] According to another aspect of the invention there is provided a method for de-palletizing stacks of blanks stacked on pallets with flat spacing layers disposed in-between, comprising the steps of: positioning at least one approximately horizontally oriented insertion tool attached to at least one displaceable gripping head in front of at least one stack of blanks; lifting at least one side of the at least one stack of blanks; and thereafter inserting the insertion tool approximately horizontally underneath the at least one stack of blanks.

[0022] During the lifting, the stack of blanks itself remains unchanged and is not deformed. The outer layers of the stack are not deformed or changed as a result of using the lifting means. When lifting up the stack and/or only one side of the stack, the insertion tool can be inserted on the underside of the stack to be picked up without touching or damaging the spacing layer or additional stacks.

[0023] The stack of blanks is advantageously lowered once the insertion tool is inserted underneath the raised stack.

[0024] To achieve a careful and easy handling of the stack of blanks, it is advantageous if the stack side facing the insertion tool is raised. A wedge-shaped opening forms as a result between the underside of the stack and the spacing layer, which offers sufficient space for inserting the insertion tool.

[0025] The stacks are handled particularly carefully if a suction element is used to lift and/or lower the stacks of blanks.

[0026] According to one modified version of the invention, it is advantageous if a vacuum and/or low pressure is generated for the suction element. The stack adheres well to the suction element if a low pressure is generated for the suction element once it comes in contact with the stack to be picked up. Suction cups, for example, can be used for this because they permit a quick and easy suction adherence between the stack and the suction cup. In addition, the adherence can be broken again easily without damaging or deforming the stack.

[0027] According to one advantageous modification of the invention, the suction element is deactivated following the insertion of the insertion tool. As a result, the suction adherence between the stack and the suction element is broken quickly.

[0028] It is furthermore advantageous if the stack of blanks is clamped in following the insertion of the insertion tool. As a result, the stack is held in place firmly on the gripping head, so that the gripping head can transfer the stack of blanks to a processing machine, e.g. a cigarette-packaging machine for producing cigarette packs.

[0029] According to yet a further aspect of the invention there is provided a method for de-palletizing stacks of blanks stacked on a pallet with flat spacing layers disposed in-between, utilizing a device of the type described above, the method including lifting up at least one side of the stack of blanks with a lifting mechanism before the insertion tool is inserted.

[0030] The advantageous effects of this lifting can be discerned from the above explanations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention is explained in the following with the aid of an exemplary embodiment and without restricting the general inventive idea.

[0032]FIG. 1 is a perspective view of a pallet loaded with stacks of blanks.

[0033]FIGS. 2a-2 c are views from the side of an exemplary embodiment of the device according to the invention in different positions based on the method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Identical or corresponding parts are given the same reference numerals in the drawings and will not be introduced again.

[0035]FIG. 1 shows a pallet 1 having a supply of blank stacks 2 stacked thereon. Spacing layers 3 for stabilizing the stack configuration on the pallet 1 are arranged between the various layers containing stacks of blanks 2.

[0036]FIGS. 2a to 2 c respectively show different operating positions of a gripping head 4 for a de-palletizing device, for example as represented in FIGS. 2 and 3 of German Patent Document DE 196 53 953 A1. The gripping head 4 is provided with a horizontal guiding device 6 for example, a pressure cylinder, which comprises a horizontally displaceable guide rod 12 with a vertical guide element 13 attached to its free end. An insertion tool 5 is arranged at the lower end of the guide element 13, which is provided with a sharp insertion edge on the front. The insertion tool 5 is designed as a flat tongue and extends downward at a slight angle to the horizontal line. Thus, its insertion edge is driven and guided vertically displaceable by moving the gripping head 4 or the guide element 13 in a downward direction.

[0037] The guiding device 6 and the guide rod 12 can be designed as pneumatic or hydraulic piston-cylinder units. For an exact positioning, however, the guide rod 13 in the guiding device 6 can also be operated with an electric motor.

[0038] For the de-palletizing operation, the gripping head 4 is positioned in front of a stack of blanks 2 containing a predetermined number of blanks. The stack of blanks 2 is held together in the center with a closing band 7. The closing band 7 also protects against dirt. On the whole, the stack of blanks 2 is shaped like a package.

[0039] The insertion tool 5 is positioned opposite a side 11 of the stack of blanks 2 positioned on the spacing layer 3.

[0040] The gripping head 4 is provided with a hold-down member 8, which is arranged in the area of side 11 that is assigned to the insertion tool 5 when the gripping head 4 is positioned in front of the stack of blanks 2. The hold-down member 8 can be moved vertically via a guide rod 17 and by means of a pressure cylinder 9. The pressure cylinder 9 is connected to a control unit 18 or, alternatively, to a regulating unit, so that the guide rod 17 can be moved precisely with the pressure cylinder 9.

[0041] A vertically guided suction cup 10 is furthermore attached to the guide rod 17 of the hold-down member 8, next to the hold-down member 8. The suction cup 10 has an elastic and flexible design and consists, for example, of rubber or a rubber-type material. The suction cup is connected via a low-pressure line 15 to a low-pressure source 16 and can be subjected to low pressure.

[0042]FIG. 2a shows the starting situation before the stack 2 is removed from the spacing layer 3. Following the positioning of the gripping head 4 in front of the stack 2, the pneumatic hold-down member 8 is lowered. The suction cup 10 is lowered at the same time as the hold-down member 8. The open underside of the suction cup 10 comes to rest on the closing band 7 of stack 2 before the hold-down member 8 touches the surface of stack 2. In this position, the vertical downward movement of the hold-down member 8 and the suction cup 10 is stopped. A low pressure is subsequently applied to the suction cup 10, so that the stack 2 is subsequently gripped at the closing band 7 (FIG. 2b).

[0043] By moving the suction cup 10 upward with the aid of pressure cylinder 9, the stack 2 is lifted up vertically on one side, so that a gap 14 forms between the underside of stack 2 and the spacing layer 3. The gap 14 is wedge-shaped as a result of lifting up only one side of the stack of blanks 2, wherein the height of this gap 14 is sufficient for inserting the insertion tool 5 into the gap 14.

[0044] Of course, the stack of blanks 2 can be lifted up completely with a differently positioned suction element, e.g. if the suction element is arranged near or above the center of gravity for the stack 2.

[0045] Once the insertion tool 5 is inserted into the gap 14 (FIG. 2c), the hold-down member 8 and the suction cup 10 are lowered further. As soon as the insertion tool 5 is inserted completely into the gap 14, the low pressure supplied to the suction cup 10 is turned off. Following this, the hold-down member 8 can be raised once more. The stack 2 positioned on the insertion tool 5 can be conveyed further and transferred with the aid of gripping head 4 to a machine for further processing, for example a cigarette packaging machine for producing cigarette packs.

[0046] The subject matter of this invention prevents the insertion tool on the gripping head 4 from damaging the spacing layer 3 or any other stacks positioned underneath it. In particular, the invention is utilized for stacks 2 that are provided with closing bands and are extremely stiff. The invention particularly makes use of the fact that the stacks of blanks 2 with closing bands cannot be deformed. Existing gripping heads 4 can therefore be retrofitted easily with a lifting means 10, in particular a suction cup.

[0047] The invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention. 

What is claimed is:
 1. A device for de-palletizing stacks of blanks stacked on pallets with flat spacing layers disposed in-between, comprising: at least one displaceable gripping head; at least one insertion tool arranged approximately horizontally oriented on the gripping head for being positioned in front of at least one stack of blanks through displacement of the gripping head and for being inserted with an approximately horizontal movement between the at least one stack of blanks and the spacing layer for picking up the at least one stack of blanks, for removing the picked up at least on stack of blanks from the spacing layer through a displacement of the gripping head; and at least one lifting means coupled to the gripping head for lifting up at least one side of the at least one stack of blanks.
 2. The device according to claim 1, including control means for activating the lifting means before the insertion tool is inserted.
 3. The device according to claim 1, wherein the lifting means is arranged for being moved vertically.
 4. The device according to claim 1, wherein the lifting means on the gripping head is arranged so that a side of the at least one stack of blanks facing the insertion tool can be raised.
 5. The device according to claim 1, wherein the lifting means comprises at least one suction element.
 6. The device according to claim 6, wherein the suction element is elastic.
 7. The device according to claim 6, wherein the suction element is a flexible suction cup.
 8. The device according to claim 1, forming a combination with the at least one stack of blanks, and further including at least one clamping device for clamping the at least one stack of blanks.
 9. A method for de-palletizing stacks of blanks, stacked on pallets with flat spacing layers disposed in-between, comprising the steps of: positioning at least one approximately horizontally oriented insertion tool attached to at least one displaceable gripping head in front of at least one stack of blanks; lifting at least one side of the at least one stack of blanks; and thereafter inserting the insertion tool approximately horizontally underneath the at least one stack of blanks.
 10. The method according to claim 9, further including lowering the at least one stack of blanks following the insertion of the insertion tool.
 11. The method according to claim 9, wherein the lifting step includes lifting a side of the at least one stack of blanks facing the insertion tool.
 12. The method according to claim 9, including raising and lowering the at least one stack of blanks with the aid of at least one suction element.
 13. The method according to claim 12, including supplying at least one of a vacuum and low pressure to the suction element.
 14. The method according to claim 12, including deactivating the suction element once the insertion tool is inserted.
 15. The method according to claim 9, including lowering the at least one stack of blanks onto the insertion tool after the insertion tool is inserted.
 16. A method for de-palletizing stacks of blanks stacked on a pallet with flat spacing layers disposed in-between, utilizing a device comprising at least one displaceable gripping head and at least one horizontally oriented insertion tool that is arranged on the gripping head and which can be positioned in front of at least one stack of blanks through a displacement of the gripping head such that the insertion tool can be inserted with an approximately horizontal movement between the stack of blanks and the spacing layer for picking up the at least one stack of blanks and removing the picked up at least one stack of blanks from the spacing layer by displacing the gripping head, the method comprising: lifting up at least one side of the stack of blanks with a lifting mechanism before the insertion tool is inserted.
 17. The method according to claim 16, including moving the lifting means in vertical direction.
 18. The method according to claim 17, including providing a control unit for controlling the lifting mechanism.
 19. The method according to claim 18, including using the lifting mechanism to lift a side of the at least one stack of blanks that is facing the insertion tool.
 20. The method according to claim 19, including providing the lifting mechanism in the of at least one suction element.
 21. The method according to claim 20, wherein the suction element is at least one of an elastic and flexible suction cup.
 22. The method according to claim 21, including clamping the at least one stack of blanks with a clamping device. 